1. Field of the Invention
The present invention relates to a battery residual amount measurement system, a computer-readable medium storing a battery residual amount measurement program, and a battery residual amount measurement method.
2. Description of the Related Art
The relative charged level of a battery that is called the state of charge (SOC) is defined as the ratio of the residual amount of charge (the battery residual amount) with respect to the charge capacity (e.g., the nominal battery capacity) of the battery. Here, measurement and monitoring of the flow of charges must be carried oat by using a method called “coulomb counting”. Actual coulomb counting processing is realized by integrating the currents that flow into the battery and the currents that flow out of the battery. Generally, a small resistor is connected in aeries to the negative electrode of the battery, and these currents are measured by using a high-resolution ADC (analog/digital converter).
Japanese Patent Application Laid-Open (JP-A) No. 2007-327971 discloses a technique relating to a battery residual amount measurement system that measures the residual amount of a battery. A method of computing the battery residual amount that accompanies charging and discharging, while taking into consideration even the undischargeable amount (the amount of electricity that is deemed unable to be discharged), and a technique of storing a undischargeable amount characteristic, that corresponds to a characteristic of the battery, in a memory are disclosed in JP-A No. 2007-327971.
The present inventors studied how to reduce system preparation costs by avoiding the need to separately manufacture battery residual amount measurement systems (the need to manufacture systems separately in accordance with characteristics), by making it possible to measure the battery residual amounts of batteries having different characteristics (e.g., charge capacities, nominal battery capacities) by a same battery residual amount measurement system.
The present inventors studied how to realize this idea in a conventional battery residual amount measurement system. However, the technique (the battery residual, amount measurement device) disclosed in JP-A No. 2007-327971, for example, is premised on the undischargeable amount characteristic of a battery being stored in advance in a memory. Therefore, even if an attempt is made to measure the battery residual amounts of batteries, that have different characteristics, by using the same battery residual amount measurement system, the undischargeable amount characteristic differs in accordance with the type of battery, and therefore, the battery residual amount may not be measured accurately in a case in which the system is used for a battery of a different characteristic instead.